Cultivating Carnivorous Plants (2015)

DARLINGTONIA

Darlingtonia californica in cultivation.

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The California Cobra Lily, Darlingtonia californica, is among the most fearsome of the pitcher plants.

Reminiscent of a snake’s head, Darlingtonia pitchers, forked tongue extended, twist outwards, posing like a

cobra ready to strike. Yet, for all their fearsomeness, the pitchers do not produce poisons, not even digestive

enzymes. In fact, Darlingtonia depends largely upon bacterial action to digest its insect prey.

Darlingtonia californica in cultivation.

As with other monotypic genera, only one species of Darlingtonia exists, californica. There are, however,

three forms of the species. The first and most common form is the typical form. This form is known as

Darlingtonia californica forma californica, although most growers do not add on the forma designation. It is characterized by having a red “tongue” in bright light and occasionally some red on the hood of the pitcher

itself.

The second form was once known by the cultivator name “Othello,” but it is now known as forma

viridiflora. A lack of anthocyanin, or red pigment, characterizes forma viridiflora. The lack of anthocyanin causes

forma viridiflora to be entirely green. In low light conditions, distinguishing forma virdiflora from the typical form

may be possible, but their flowers set them apart. Forma viridiflora’s flowers entirely lack red pigmentation,

whereas the typical form’s feature red sepals.

The third form is rare, entirely red, and, like many of its Sarracenia cousins, known as forma atropurpurea.

CULTIVATING CARNIVOROUS PLANTS

Although some typical plants may initially show entirely red coloration, these revert back to the typical

coloration pattern upon reaching adulthood. Entirely red adult pitchers are the characteristic that

distinguishes forma atropurpurea.

There is some indication that other forma exist. Recent expeditions into the field discovered pitchers with

red a ring of red pigmentation around the “windows” on the pitcher hood. Other reported mutations include

color variations and pitcher variations. More fieldwork is necessary before determining whether these forma

exist.

Habitat

Darlingtonia californica off the Rocky Creek Trail in Oregon.10

Darlingtonia is unique among carnivorous plants because it grows in two distinct habitats - coastal and

montane. Coastal plants experience warm day temperatures, around 70° - 75° F (21° - 24° C), and high

humidity from the frequent coastal breezes. Montane plants, in contrast, can experience very hot daytime

temperatures, up to 110° F (43° C), and much lower humidity.

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Coastal plants often inhabit

what is thought of as a “typical”

carnivorous

plant

habitat,

sphagnum bogs. In contrast,

montane plants often inhabit

fens, i.e. marshy, alkaline habitats

atop serpentine soils. Snowmelt

and cold springs feed these fens,

so the roots of the plants remain

cool when temperatures soar.

(Coastal plants, however, always

have cool roots because the air

temperature does not rise very

far, and the roots of plants are

often shaded by plant growth).

Both

coastal

and

montane

habitats experience cool night

time temperatures during the

height of summer, often down to

Darlingtonia in the wild at Darlingtonia State Natural Site

60° F (16° C).

(Formerly known as Darlingtonia Wayside).

Of course, there is habitat variation, and some features of coastal habitats can occasionally be found in

montane habitats, and vice versa, but, for the most part, these two habitats are entirely separate. Recent

research has indicated that there might be three different habitats. To date, no cultivation studies have been

conducted regarding this claim, and it is unknown whether there are actually three different habitats that

Darlingtonia can inhabit. Currently, cultivation studies only support division into coastal and montane habitats.

In Cultivation

The separation between coastal and montane habitats remains in cultivation. Darlingtonia originating

from coastal regions require conditions similar to those they experience in nature, i.e. constantly cool roots

and cooler temperatures. Darlingtonia originating from montane regions, in contrast, are better able to tolerate

a wider-range of conditions, including hot daytime temperatures, as long as night temperatures are cool.

For both coastal and montane Darlingtonia, the key to long-term cultivation is cool nighttime

temperatures, and, with coastal Darlingtonia, cool daytime temperatures as well. Most growers find that

montane-region Darlingtonia are easier to grow long-term; replicating coastal California’s and Oregon’s climate

year-round is difficult. If established, montane plants can experience warm to hot roots during the day

without issue, as long as the plant experiences nighttime temperature drops to near 60° F (16° C).

The easiest way to keep roots cool is to use an airy media mix, such as one part long fiber sphagnum and

one part perlite. Using large, light colored, especially white, pots helps keep roots cool. Flushing the pot with

chilled water at least once per day is also advisable.

CULTIVATING CARNIVOROUS PLANTS

Typical Darlingtonia flower.11

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My standard growing guide for Darlingtonia follows:

✵

Media: Darlingtonia do well in a mix of one part sphagnum to one part perlite or orchid bark. It

is not known whether adding an ultramafic rock, such as serpentinite, would increase growth.

✵

Moisture: Watering via the tray method, and always keeping some water in the tray, is probably

the easiest way to meet the moisture and humidity requirements of Darlingtonia during the

growing season. It is also advisable to flush the pot with chilled water at least once a day,

although many plants will be subjected to a constant flow of chilled water in the wild. During

dormancy, soil should remain moist, but not soaking in order to prevent rot.

✵

Humidity: Coastal Darlingtonia need higher humidity than montane Darlingtonia. In general, the

species has the same humidity requirements as its cousins, the Sarracenia.

✵

Pot Size: Pots should be much larger than the plant in diameter, but do not need to be very

deep. The plant will spread via lateral rhizome growth in good conditions, meaning the pots

must be large to accommodate the growths. The roots, however, do not ordinarily grow very

deep compared to other plants.

✵

Feeding: Feeding Darlingtonia is difficult. Unlike Sarracenia, Darlingtonia does not appear to

benefit from the placement of a few osmocote-type pellets near their roots. Nor does

Darlingtonia benefit from foliar fertilizer. It may, however, benefit from insects added to the

pitchers themselves.

✵

Temperature: Montane Darlingtonia can tolerate a wide range of above-freezing temperatures

during the growing season, but care should be taken to try to restrict their upper limit to 90° F

(32° C) with temperature drops to 60° F (15° C) at night. Coastal Darlingtonia should experience

cooler temperatures, never exceeding 75° F (24° C).

✵

Dormancy: Dormancy is required for Darlingtonia. In cold climates, plants can be left outdoors,

but, in warmer climates, plants should be chilled in the same manner as Sarracenia.

✵

Propagation: Darlingtonia can be propagated via the following methods:

Division: The easiest way to propagate Darlingtonia is to divide the smaller, lateral

offshoots from the larger, more mature plants. It is better to wait for the offshoots to

form their own root systems and become somewhat established before dividing them

because, otherwise, they could easily die from lack of water.

Seed: Darlingtonia may also be propagated via seed. Fresh seed should be sown on a

suitable media and cold stratified for six weeks. The easiest way to do this is to cover

the pot with plastic wrap and place in the refrigerator for six weeks. Then, the pot

should be removed and placed in a location with temperatures and light similar to adult

plants.